Experimental evidence of the hybridization of the electron states of an impurity and the conduction band in the HgSe:Fe system

X-ray absorption spectra from iron donor impurities in mercury selenide have been analyzed in a concentration range where the Fermi energy of conduction electrons is close to the energy of the donor d level. At high impurity concentrations, the resulting spectrum corresponds to the completely filled donor state and coincides with the spectrum of a bivalent iron ion. A transition to an intermediate-filling state is observed with decreasing the concentration. The spectra are quantitatively analyzed in a model implying the existence of a mixture of ions that contain and do not contain a donor electron in a bound state. It has been found that such a model is significantly inconsistent with the experimental data. It has been shown that the concentration dependence of the x-ray spectra corresponds to the manifestation of the significant hybridization of localized and delocalized donor electron states in the conduction band.     

Angle-resolved photoemission study of a vacancy-induced state in substoichiometric VC

A vacancy induced state has been identified at about 1.8eV binding energy on the (100) face of VC_0.80 using angle-resolved photoelectron spectroscopy. The recorded spectra are compared with calculated spectra for VC_1.0 and the results show that the origin of the observed state cannot be accounted for by the energy band structure of VC_1.0. Photoemission spectra recorded after exposing the clean surface to O₂ and CO are also presented and used in a discussion of the sensitivity of the vacancy induced state to surface contamination.     

Potential reduction interior point algorithm unfolding of neutron energy spectrum measured by recoil proton method

A reconstruction algorithm for unfolding neutron energy spectra has been developed, based for the first time on the potential reduction interior point algorithm. This algorithm can be easily applied to neutron energy spectrum reconstruction in the recoil proton method. We transform the neutron energy spectrum unfolding problem into a typical nonnegative linear complementarity problem. The recoil proton energy spectrum and response matrix at angles of 0^o and 30^o are generated by the Geant4 simulation toolkit. Several different neutron energy test spectra are also employed. It is found that this unfolding algorithm is stable and provides efficient, accurate results.     

Count-rate,linearity, and performance of new backgammon detector technology

The meander wire backgammon technology has high levels of flux and spatial linearity across a wide range of energies. One of the attractive features of these technologies is the stability of response and robustness under long X-ray exposure, compactness, and portability. A key problem historically has been the limited range of count-rate for processing to the optimum resolution. We report dramatic advances in this and other areas appropriate for high-accuracy experiments including tests of quantum electrodynamics, fundamental relativistic atomic physics, X-ray calibration, and crystallography. We illustrate this technology applied to the Kα_1,2 spectra of titanium, chromium, and copper. The quality of the spectra permits deeper insight into atomic and solid state science and permits accurate measurement of energy and relativistic atomic physics processes, below 1-μm accuracy or down to 1 ppm in energy.     

类硼离子基态的精细结构(英文)

以多电子精细结构哈密顿的球张量形式为基础,借助不可约张量理论,建立了类硼离子基态精细结构能量的解析表达式.完成了所有角向积分和自旋求和计算,使精细结构能量表示为若干个径向积分之和.在此基础上计算了类硼体系(Z=5~8)基态精细结构能量,计算结果与实验数据符合得较好.     

Simulation of the Processes of Isomerization of Complex Molecules and of Their Spectra with Time Resolution

Based on the method developed earlier to calculate the dynamic electronic-vibrational spectra of complex molecules with allowance for isomeric transformations, a more general method has been developed making it possible to model the spectra of several isomeric forms in any number depending on the problem posed. Population dynamics analysis of the energy levels of isomers is possible. Computational algorithms have been developed and optimized, and a specialized software has been developed for a PC and a supercomputer (of the type MVS 1000). Computer experiments were carried out, and the possibility of simulating dynamic spectra and kinetic intramolecular processes in real time for complex compounds with allowance for their intermolecular transformations is shown.     

Investigation of the electronic structure of the BiSBr and BiSeBr clusters by density functional method

The energy levels of valence bands (VB) of the BiSBr and BiSeBr crystals have been calculated for investigation of the photoelectron emission spectra of BiSBr, BiSeBr and BiSI crystals. The molecular model of this crystal has been used for the calculation of VB by the Density Functional Theory (DFT) method. The molecular cluster, consisting of 20 molecules of BiSBr, BiSeBr, has been used for calculations of averaged total density of states, including atom vibrations. The spectra of the averaged total density of states from VB of BiSBr and BiSeBr clusters have been compared with the experimental photoelectron emission spectra from VB of BiSI crystals. The results clarify that the atomic vibrations in A⁵B⁶C⁷ type crystals with chain structure create a smoother appearance of the averaged total density of state spectrum and the experimental X-ray photoemission spectra (XPS).     

含顺磁杂质超导体中的束缚态

本文利用广义正则变换和自洽场方法,讨论了单个杂质对超导体的影响。证明在磁性杂质附近,可能形成一个束缚态的元激发,其能量位于能隙之中。求出了能级和波函数的解析表达式,并计算了束缚能级所引起的附加电磁吸收。讨论了与此有关的隧道和高频吸收实验。此外,还讨论了非磁性杂质对连续谱元激发的影响及杂质附近能隙的变化。     

Two-electron impurity in the parabolic quantum dot: Uncertainty relation and perturbation approach

Two-electron impurity states in parabolic confinement have been investigated. We have estimated the ground-state energy value, using the Heisenberg uncertainty relation. Using variational methods the ground state energy and wave function of the single-electron impurity problem have been achieved. The dependence of ground-state energy and Coulomb electron–electron interaction energy correction on the QD size is studied. The dependence of the state exchange time on the QD radius has been calculated. It has been shown that the presence of the impurity leads to the appearance of negative values of the energy of the system on the one hand, and to the saturating character of the state exchange time.     

Energy degradation of electrons in krypton

The problem of energy degradation of electrons in krypton has been investigated using the Monte Carlo method. The results are presented as the probability distributions of the number of ionizations, the Fano factor, the mean energy per ion pair and the degradation spectra for source energies up to 4 keV.     

类氟离子基态的精细结构

以多电子精细结构哈密顿的球张量形式为基础,借助不可约张量理论,建立了类氟离子基态精细结构能量的解析表达式.完成了所有角向积分和自旋求和计算,使精细结构能量表示为若干个径向积分之和.在此基础上对类氟体系(Z=9～13)基态的精细结构能量进行了具体计算,计算结果与实验数据符合得较好.     

Fully rotationally resolved ZEKE photoelectron spectroscopy of C6H6 and C6D6: photoionization dynamics and geometry of the benzene cation

A comprehensive set of spectra for the benzene cation and the perdeuterated benzene cation has been recorded with full rotational resolution using zero kinetic energy photoelectron spectroscopy (ZEKE) at high resolution (up to 0.2 cm^?1), using a slow-rising extraction pulse. With different rovibronic levels in the S₁ 6^l state as intermediate resonance, the rotational transitions to the vibronic ground state of the cation have been recorded using two-colour, two-photon resonance enhanced multiphoton ionization. A simple spectator model has been employed to simulate the intensities of the ZEKE transitions. By fitting the simulations to the recorded spectra, improved values for the rotational constants and the Coriolis coupling parameters of benzene and perdeuterated benzene have been obtained. The CC and CH bond lengths of the cation have been deduced. The spectator model is shown to be reliable despite the fact that no specific allowance is made for the effect of final state interactions on the signal intensity.     

Comparative analysis of characteristic electron energy loss spectra and inelastic scattering cross-section spectra of Fe

The inelastic electron scattering cross section spectra of Fe have been calculated based on experimental spectra of characteristic reflection electron energy loss as dependences of the product of the inelastic mean free path by the differential inelastic electron scattering cross section on the electron energy loss. It has been shown that the inelastic electron scattering cross-section spectra have certain advantages over the electron energy loss spectra in the analysis of the interaction of electrons with substance. The peaks of energy loss in the spectra of characteristic electron energy loss and inelastic electron scattering cross sections have been determined from the integral and differential spectra. It has been shown that the energy of the bulk plasmon is practically independent of the energy of primary electrons in the characteristic electron energy loss spectra and monotonically increases with increasing energy of primary electrons in the inelastic electron scattering cross-section spectra. The variation in the maximum energy of the inelastic electron scattering cross-section spectra is caused by the redistribution of intensities over the peaks of losses due to various excitations. The inelastic electron scattering cross-section spectra have been analyzed using the decomposition of the spectra into peaks of the energy loss. This method has been used for the quantitative estimation of the contributions from different energy loss processes to the inelastic electron scattering cross-section spectra of Fe and for the determination of the nature of the energy loss peaks.     

Energy transfer processes in two different bifluorophoric laser dyes

The mechanism of intramolecular energy transfer in two bifluorophoric laser dyes has been investigated by measurements of laser parameters, excited state absorption and phosphorescence spectra. The new value found for the dimethyl-POPOP triplet energy (48.0 kcal/mole) accounts for the different behaviour of the two classes of bifluorophoric dyes used in this investigation.     

Auger and electron energy loss spectra of adsorbed species: α and β states of carbon monoxide and nitrogen on W(100)

Auger and electron energy loss spectra have been recorded for both α and β chemisorbed states of carbon monoxide and nitrogen on W(100). The α state spectra have been analysed with reference to results for the gas phase molecules, those for the β states have been analysed following a quasi-atomic final state model. The results illustrate both the potential and the limitations of AES and ELS in surface chemical analysis.     

Co2+:ZnAl2O4晶体电子光谱及其2E态双重谱线结构的Jahn-Teller效应研究

在中间场耦合图象中,利用Racak不可约张量算符法和Wigner－Eckart定理,建立了3d⁷(C_3v)电子组态的完全能量矩阵;利用该矩阵研究了Co²⁺:ZnAl₂O₄晶体的电子光谱,理论与观测十分吻合．首次定量地解释了2E态的双重谱线结构,并从理论上预言了⁴A₂基态2.93cm^-1的零场分裂(ZFS)．研究结果定量地表明,Jahn－Teller效应所致Co²⁺:ZnAl₂O₄晶体Co²⁺中心局域结构的畸变假设是合理的．     

Properties of a two-dimensional semimetal in a strong magnetic field

A system of two-dimensional electrons and holes ha s been investigated in a strong magnetic field, when it is sufficient to take into account only the ground Landau level. It has been shown that the interaction of electrons and holes can lead to an ordered state. In this problem, the exchange interaction in electron and hole subsystems is significant. The following two cases have been considered: (a) there are one electron and one hole valleys, and at some magnetic field strength, there exists an ordered state, as in an excitonic insulator; and (b) there exist one electron and two equivalent hole valleys (as in the experiment performed by Kvon et al. [1]), and the hole system has an ordered state of the Stoner ferromagnetic type in a specific range of magnetic field strengths. The spectra of elementary excitations of the Bose and Fermi types have been obtained. The Fermi excitations have a gap in the energy spectrum, whereas the Bose excitations in the ordered states begin with zero (to these excitations there corresponds an electric dipole moment). The self-consistent field approximation has been used, which is exact when the numbers of electrons and holes are equal to each other.     

On the valence shell binding energy spectrum of carbonyl sulphide

The valence shell binding energy spectrum of carbonyl sulphide (10–45 eV) has been measured using both binary (e,2e) and dipole (e,2e) electron impact spectroscopy and calculated by the 2ph-TDA many body Green's function technique. The spectrum shows extensive structure above 20 eV, indicating a major breakdown of the quasi-particle picture for ionization of COS. The calculation is in good agreement with the present experimental and literature ESCA binding energy spectra. Binary (e,2e) spectra at two azimuthal angles support the theoretical prediction that this extensive final ion state structure arises primarily from ionization of the COS 6σ and 7σ inner valence electrons.     

Fluorescence spectrum characteristic of ethanol--water excimer and mechanism of resonance energy transfer

The steady-state fluorescence spectrum characteristic of ethanol--water excimer has been studied in this paper. By analysing the features of the sharp emission spectrum with fine structures in a shortwave band and the characteristics of the broad and featureless fluorescence peaks in the longwave band, one can conclude that the excimers are formed between the new ethanol--water cluster molecules in the excited state and the ground state through the interaction among different chromophores. The excitation spectra in the two fluorescence bands have been studied, and their emission mechanisms have been ascertained based on the energy transfer theory. Furthermore, the critical distance of the resonance energy transfer has been calculated.     

Superliquid state of an exciton mixture with small exciton radii in molecular crystals

The energy spectrum of excitons with a small radius in a superliquid state in molecular crystals has been investigated. A more complicated structure of the exciton energy spectrum with a number of equivalent minima for k 0 has been considered. The problem was solved as that of determining the energy spectrum of a mixture of various types of non-ideal exciton gases in a superliquid state, corresponding to the individual exciton energy minima. The appropriate branches of the energy spectrum of elementary excitations (hydrons) have been determined and the conditions for their stability have been investigated.